Mosquito diseases, Zika, Malaria, Dengue

An Aedes Albopictus mosquito, one of the Aedes species that is responsible for Dengue fever, Chikungunya and Zika. The other pest is Aedes Aegypti which looks very similar and has the same distinctive white markings. However, just because the mozzie has white bands doesn’t mean it’s infected with anything! It’s probably just irritating but harmless. Relax. Well, kill it then relax.

Mosquito Disease Prevention

Zika virus

The CDC (the US Centre for Disease Control) informs us that Zika mosquitoes can be found in the Caribbean, Central and South America, Pacific Islands, Singapore, and within the United States, specifically Florida (at the moment). The effects are generally mild but the concern is about a probable link with brain defects in babies. If in any doubt head elsewhere for your vacations BUT if pregnancy is not an issue due to contraception, age or gender then this may be a good time to travel in Latin America as competition for rooms and sun beds is likely to be lower than normal.

Pregnancy and travel

Only pregnant women have been advised to reconsider their plans to visit countries affected by Zika. It is thought that within the female body the virus can travel across the placenta and affect the health of an unborn baby. There has been a surge in microcephaly – in which the baby’s brain does not develop properly – in Brazil.

Pregnant women should reconsider their travel plans and travellers should seek advice from a health professional before departing. Pregnant women who have to travel should take ‘scrupulous’ measures to avoid being bitten by mosquitoes. The US Centers for Disease Control says women trying to get pregnant should “talk to your doctor about your plans to become pregnant and the risk of Zika virus infection and strictly follow steps to prevent mosquito bites during your trip.”

Is it safe to get pregnant after visiting?

The CDC says Zika lingers in the blood for approximately a week. And: “The virus will not cause infections in a baby that is conceived after the virus is cleared from the blood. “There is currently no evidence that Zika virus infection poses a risk of birth defects in future pregnancies.”

What about men?

Zika can be passed through sex from a person who has Zika to his or her partners, even if the infected person does not have symptoms at the time.

It can be passed from a person with Zika before their symptoms start, while they have symptoms, and after their symptoms end.

Though not well documented, the virus may also be passed by a person who carries the virus but never develops symptoms.

Studies are underway to find out how long Zika stays in the semen and vaginal fluids of people who have Zika, and how long it can be passed to sex partners. Zika can remain in semen longer than in other body fluids, including vaginal fluids, urine, and blood.

It is thought the virus can persist in semen for two weeks after a man recovers from an infection. Very few countries have specific advice for men. Public Health England is taking a safety-first approach after one suspected case of sexual transmission. The organisation says the risk of spreading the virus through sex is “very low” and at this stage only “theoretical”. But it recommends using condoms if you have a pregnant partner or one who might become pregnant. This should be done for 28 days after coming home and if you have no symptoms, and for six months if Zika symptoms do develop.

What are Zika symptoms? And treatment?

If you have symptoms such as fever, a rash, joint pain or red eyes, which develop either on holiday or when you return, then you should speak to a doctor. CDC says: Take medicine, such as acetaminophen or paracetamol, to relieve fever and pain. Do not take aspirin, products containing aspirin, or other nonsteroidal anti-inflammatory drugs such as ibuprofen. Get lots of rest and drink plenty of liquids. Prevent additional mosquito bites to avoid spreading the disease.

• if you use good mosquito repellant containing Deet, Picardin or IR3535 (safe for pregnant women) on bare skin outdoors (especially legs!) and sleep in screened or air conditioned room then your chance of getting Zika is very, very low.

• Just because a very small portion of the population get Zika (Florida September 2016 = 43 cases, population 20 million) does not mean you should panic! We were in Singapore two months ago wearing T shirts, shorts and sandals for a wonderful week, no repellant, saw no mosquitoes, had no bites at all, but the country is on the Zika list because poor immigrant workers in a remote area were infected.

• But it’s definitely worth avoiding highly infected areas such as Puerto Rico – now experiencing high levels of crime and a Zika epidemic, with about 17,000 cases according to CDC in mid-September. Locally acquired (via mosquito, not thru traveling) Zika cases as of mid-September 2016: Puerto Rico 17,315; US Virgin Islands 265; Florida 43.

Malaria

Malaria is at large in over 100 countries of the world, and one – two million people die of malaria every year.

In the last few years the UK saw a 30% rise in travellers infected with malaria, mostly contracted in West Africa (Nigeria and Ghana 40% of total) and India (11%).Aedes Albopictus disease found, though not necessarily rampant: SE Asia (even Singapore! ), India, West Africa, Central America, Brazil, USA East Coast, Italy, Greece, Croatia, Portugal, Spain, Netherlands, South France.

Malaria Treatments and Prophylactics (Preventative Medicines)

Some preventatives can be ineffective, while others can instigate health problems – making you nauseous or turning you into quivering, psychotic jelly. Many experienced travellers only use chemicals in high risk areas, but the choice is yours. One thing that won’t turn you into psychotic jelly is travel insurance, protection without the shakes!

High risk e. g. some parts of Asia, Oceania, use chloroquine and proguanil (Paludrine), or mefloquine (Lariam) or malarone.

Very high risk e. g. sub-Saharan Africa, parts of the Caribbean, the north half of Latin America, and Far East (esp. Thai/Cambodia and Thai/Myanmar borders, Papua New Guinea), use:

– Malarone if available, or perhaps Mefloquine (Larium). In sub-Saharan Africa chloroquine and proguanil is rated as 50%-70% effective, while mefloquine (Lariam) is 90% effective against malaria but can have unpleasant side-effects such as : nausea, panic attacks, fits, manic depression and a tendency to bark at the postman. A study (reported in The Times 20/9/00) estimated that 1 in 140 Lariam users suffered ‘socially disabling neuropsychiatric side-effects. ‘

– Malarone (atovaquene), as effective as Larium (i. e. nearly 100%) but no psychological side-effects, though 14% of trial users reported some headaches and dizziness (Sept. /00). Also you only need to take it for only 7 days after leaving a malaria zone, as opposed to 28 days for Lariam. In UK it’s available on prescription at BA travel clinics when there is a specific health need.

– Qinghaosu, Chinese wormwood, a naturally produced herb has been used by the Chinese since mid-70s, and is now used in combination with other drugs, especially mefloquine – also known as Artemisinin – where the malaria parasite is particularly drug resistant. Very effective, but not widely available.

– Doxycycline, an antibiotic (for treatment of chest and other infections), is widely used as a malaria treatment.It’s especially popular in the Far East but becoming less effective as local buzzers develop resistance e. g. Thailand and Laos. However it makes the skin sensitive to sunshine so it’s not good for beach holidays. It needs to be taken with plenty of water to prevent it sticking in the throat, and you should consume probiotics of some sort to restore healthy bacteria to your system – yoghurt or some other dairy products for example.

After Traveling

Take care that health problems such as fever or flu-like illness developing up to 1 year after travel is not put down to flu. Clearly inform your doctor of the possibility of malaria.

Symptoms of Malaria: From infection to symptoms generally takes 1- 4 weeks, but can take up to one year. Initial symptoms in adults for both malaria and West Nile virus: flu-like illness, weakness, dizziness, headache, fever, muscular pains, vomiting, diarrhoea.

Initial symptoms in children: any of the above plus convulsions, coughing and rapid shallow breathing.

Dengue Fever

Dengue fever is a mosquito-borne tropical disease caused by the dengue virus.Symptoms typically begin three to fourteen days after infection. This may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash. Recovery generally takes less than two to seven days. In a small proportion of cases, the disease develops into the life-threatening dengue hemorrhagic fever, resulting in bleeding and dangerously low blood pressure occurs.

Dengue is spread by several species of mosquito of the Aedes type, principally A. aegypti.

West Nile virus

West Nile virus is a problem in the USA which has killed two or three hundred people in the last two years.

The viral transmitting mosquitoes have now appeared in southern Europe including Portugal, Spain and France. So how can you avoid these sometimes deadly infections?

The best way to avoid Malaria, Dengue Fever and West Nile virus (not to mention rarer but equally unpleasant health threats such as Encephalitis, Triple E, Yellow Fever, Rift Valley fever and more) is to keep the little stingers off you.

Chikungunya

Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash.

The disease shares some clinical signs with dengue, and can be misdiagnosed in areas where dengue is common.

There is no cure for the disease. Treatment is focused on relieving the symptoms.

The disease occurs in Africa, Asia and the Indian subcontinent. In recent decades mosquito vectors of chikungunya have spread to Europe and the Americas. In 2007, disease transmission was reported for the first time in a localized outbreak in north-eastern Italy. Outbreaks have since been recorded in France and Croatia.

Most patients recover fully, but in some cases joint pain may persist for several months, or even years. Occasional cases of eye, neurological and heart complications have been reported, as well as gastrointestinal complaints. Serious complications are not common, but in older people, the disease can contribute to the cause of death. Often symptoms in infected individuals are mild and the infection may go unrecognized, or be misdiagnosed in areas where dengue occurs.

Transmission

Chikungunya has been identified in over 60 countries in Asia, Africa, Europe and the Americas.

The virus is transmitted from human to human by the bites of infected female mosquitoes. Most commonly, the mosquitoes involved are Aedes aegypti and Aedes albopictus, two species which can also transmit other mosquito-borne viruses, including dengue. These mosquitoes can be found biting throughout daylight hours, though there may be peaks of activity in the early morning and late afternoon. Both species are found biting outdoors, but Ae. aegypti will also readily feed indoors.

After the bite of an infected mosquito, onset of illness occurs usually between 4 and 8 days but can range from 2 to 12 days.

Triple E virus: Eastern Equine Encephalitis

Fresh into the mosquito-borne disease spotlight is the USA’s Triple E virus, Eastern Equine Encephalitis, which is found in north eastern US locations such as Rhode Island. It is rarely transmitted to humans (averaging 5 cases per year; birds are the main recipient of Triple E), but when it is, it’s deadly, killing a third of those infected. There is no cure or vaccine, so keeping mozzies off is the only defence.

Mosquito varieties

Here an Anopheles stephensi mosquito is getting a blood donation from a human host through its personal syringe and expelling a drop from it’s abdomen after having drunk too much. Anopheles mosquitoes are found from Egypt to China.

Anopheles mosquitoes – the ones that transmit malaria – fly mainly at dusk and dawn, so prepare yourself for this whining and dining time, depending on your region.

Aedes mosquitoes that are responsible for Zika virus, Yellow Fever, Chikungunya Fever, Dengue Fever and Nile Virus fly during the day too, tho’ they are more aggressive at dusk and dawn. So in Aedes danger areas all day precautions are advisable.

No-see-‘ums

These tiny fleas – almost invisible – live around beaches and rivers and bite mainly about dusk, particularly after rainfall. The result of their bite is out of all proprotion to the size of the insect , with massive swellings the size of a hand quite normal. Normal repellants, including deet-based, are useless against these critters though the US army believes they know a product that works – Avon’s Skin So Soft.

Gallinippers

The appearance of a giant species of mosquito in Florida is expected this year due to recent tropical storms. Gallinippers (Psorophora ciliata) are 20 times bigger an ordinary mosquito, the size of a US 25-cent piece, and already known in eastern US. They bite not only at dusk and dawn but during the day too and apparently being bitten feels like ‘having a hot nail drived into your back’. The good news is that Gallinippers are extremly visible and audible, landing on flesh with a heavy thump, so they’re irritating but easy to kill. Furthermore they don’t appear to carry malaria or other mosquito borne diseases.

How Mosquitoes find you

Research from London School of Hygiene and Tropical Medicine indicates that mosquitoes source their prey in three stages:

• From distances of 10-50m mozzies use smell, particularly CO2 – in other words your exhalations, so if you breathe heavily thru exercise you’ll be setting up a perfect feed-on-me marker.

• When aroused by the smell of CO2, the biters look for living creatures within a range of 5-15m. So wear camouflage/something non-contrasting! Unfortunately this contradicts the idea that mozzies don’t like light colours (as they become more visible against, for example, white).

• Once within a couple of metres of a potential target, mosquitoes zero in on body heat.

Researcher Dr van Breugel remarked that this search/find strategy is very effective and makes it very difficult to avoid mosquitoes. The more of sensory cues that you can disrupt, the less likely the critters are to find you.

• However! It’s also thought that some species of mosquito (tropical?), such as the ones that carry malaria, prefer bacteria and sweat to CO2. Unfortunately tropical heat and humidity triggers sweat and bacteria!

Avoiding Mosquitoes

Zika, Dengue and Chikungunya are spread by the Aedes mosquito species which is most active during the day but also flies at dawn and dusk.

People are advised to:

* Cover up with long-sleeved shirts and trousers * Use insect repellents such as those containing DEET, picaridin or IR3535, the stronger the better though, for example, DEET over 50% is not good for delicate skin. Put it on clothes instead (T-shirt near neck and arms, shorts near bare legs etc.) If you prefer a natural product try one of these repellents. * Apply sunscreen before using applying insect repellent * Keep doors and windows closed and to use air conditioning

p.s. If you get bitten and the spot is itchy, try ‘ironing’ it with a hot cup of tea or coffee – it will magically disappear! Alternatively try squeezing lemon juice or apple cider vinegar or fresh cut onion/garlic onto it.

Indoors, hunt to splat. Look under beds, shake curtains, check dark places. In extremis spray the room with (esp. pyrethrum) insecticide, if it has window nets or air conditioning.

Electric anti-mosquito mats are preferable for all-night protection rather than smouldering coils, as coils tend to run out before dawn, and are smelly, unhealthy devices anyway. But they are very effective.

When travelling in more primitive surroundings sleep under a net, treated with permethrin if possible. If not, mosquito coils are default best system.

Finding and preventing mosquitoes at home

A typical abandoned plant pot in the garden now breeding mosquito larvae.

If you’re living in a mosquito area for a while it’s worth checking around your property (or even cast an eye over the neighbour’s) for stagnant water that has collected in discarded containers, the hidden bottom of plant pots or ponds – large or small – that have become mosquito farms, even if you have added fish to eat the larvae as they may be the wrong type of fish! Check them VERY closely for writhing little screw shapes (larvae) under water or tiny mosquitoes parked on the edge of the water. I once lived in an apartment in Venezuela that had netting on all windows, yet we were endlessly savaged by the little blighters. We spent days checking all netting for tiny holes, then found, months later, that the mozzies were breeding in the small bowl of water growing ivy in the middle of the dining table.

Mosquito larvae-eating fish

Female mosquitoes can lay hundreds of eggs in still/stagnant water. These float on the surface for a couple of days before hatching into larvae which then live in the water for around 10 days. In the next stage they become pupae (baby mosquitoes) that float on the surface for 48 hours before developing into adult mosquitoes.

Mosquitoes breed in stagnant fresh water so moving pond water – via a fountain or waterfall with the help of a pump – could prevent that. Some fish also enjoy mosquito-larvae ready-meals, such as goldfish, mosquito fish, minnows, killifish, and guppies, but check that they’re doing the job and perhaps don’t feed them much or at all as they may prefer your fish food to nature’s bounty.

Gambusia affinis, aka mosquito fish, are very adaptable and tough and widely found in southern USA. They look similar to guppies and will aggressively consume hundreds of mosquito larvae along with any other creatures that might be around – such as tadpoles or other fish – so they’re brilliant at keeping mosquitoes under control but not at sharing their environment with more colorful fish.

Oils and chemicals

Bti and Oil can be added to water to reduce mosquitoes. Bti is commercially available to pond owners and is a naturally occurring bacterium that kills mosquito larvae but is not harmful to fish, pets, wildlife, or humans. It is frequently sold in doughnut shapes called Mosquito Dunks or Mosquito Bits.

Oil is an old remedy for mosquito control and was used in large quantities years ago when the Panama Canal was being built. Mosquito larvae cling to the under-surface of the water to breathe but a coating of oil can prevent this. In Panama they used diesel fuel but this is damaging to plants, fish and insects. Unfortunately cooking oils are neither very effective nor clean, leaving a coating everywhere that is difficult to remove.

Mosquito Traps

There are now traps available that catch significant numbers of Aedes Albopictus, the most elusive mosquito. The trap produces an air current of ammonia, fatty acids and lactic acids that imitates the smell of a human body. With the addition of carbon dioxide, the efficiency of the trap improves further. These traps attract the insects by smell and then sucks them onto a mesh by vacuum, where they dehydrate and die. However. . if you are between the mosquito source and the device they will attack you first, so the location of the device is vital and if the insects are approaching from all directions we can’t see how a trap would help. The traps are expensive (over $500) and still under development. The Mosquito Magnet is one that seems to work well in some environments though it’s efficiency over several years is questionable.

Mosquito Repellents

– Deet. The most potent mosquito repellents contain lots of Deet (Diethyl-toluamide), so check out the ingredients. 25% Deet is good, 50% is excellent and 100% Deet will force mosquitoes to leave the country; trouble is it will also dissolve your skin, so only use it on clothes or nets. Be wary of using deet on the skin of small children. Try refined oils (see below) as an effective alternative.

Deet news 2015: Mosquitoes evolve very quickly according to Dr James Logan, London School of Hygiene and Tropical Medicine. Research suggests that mosquitoes simply do not like the smell of Deet but appear to get used to it after a short time as their antenna receptors became de-sensitized. Nevertheless Dr Logan says that deet is effective at first/in many cases and visitors to high risk areas should continue to use it.

– Picaridin and IR3535 are also recommended mosquito-effective ingredients and are safe for pregnant women

– Mosiguard is relatively natural (citrodiol and eucalyptus) and often very effective, so starting with that and saving the Deet for heavy duty mozzie attacks is worthwhile.

– Refined lemon eucalyptus oil, Greek Catnip oil, Lavender oil, Tea Tree oil, Soy Bean oil and citronella oil, all are disliked by insects; but dilute them with some kind of carrier oil, such olive, sunflower or sesame, a few drops per teaspoon of carrier oil is generally effective but the product and strength needed will depend on the type of mosquitoes in your environment. Also/alternatively bath or shower with lemon gel.

– NeemCare Herbal Insect Repellent. Neem tree oil is used in Ayurvedic medicine and is burned in India to repel insects. It is now on the market as a general repellent and in tests has successfully repelled the voracious midges that plague the Scottish Highlands as well as mosquitoes. If mosquitoes do get through the defences, trials indicate that Neem oil also reduces the severity of the body’s reaction to the bite. Personally tested when travelling in Myanmar, it worked perfectly. Available in health stores and pharmacies, it also works against head lice.

– Vitamin B1/B12. Consistent anecdotal evidence suggests that mozzies hate the smell of B1. Take 100mg a day, starting a few days before your trip. Others swear by B12. They’re both worth trying if you plan to spend a while in mosquito disease zones.

– Fish Oil capsules. e. g. Cod Liver Oil. It must be unrefined so there is a hint of fishy smell about your person. Take a few days before leaving to build up the odour. Think about it. . . fish eat mozzies and their larvae, so a mosquito will have an intense aversion to fish. Some people swear by this solution.

– Quercetin. You can also strengthen your body’s health system before travelling by taking an anti-inflammatory called quercetin, which is especially effective when taken with Vitamin C.

– One ‘deterrent’ is smelly socks! Scientists in Tanzania have discovered that mosquitoes prefer the odour of very smelly socks than humans, by a factor of 4: 1. In other words – a) wash your feet after a long hike and put your socks well away from your camp b) or you could try creating a box shrouded in insecticide cloth to kill the little buzzers.

– Electric ‘vape’ mats work well in rooms, are relatively inoffensive and last longer than coils, but check local voltage and socket type.

– Electronic buzzers/sonic deterrents do not work as far as our experience goes.